1. Field of the Invention
The present invention relates generally to a method and apparatus for storing, retrieving, and distributing various kinds of data, and more particularly, to an improved database architecture and method for using the same.
2. Art Background
Over the past 30 years, computers have become increasingly important in storing and managing information. During this time, many database products have been developed to allow users to store and manipulate information and to search for desired information. The continuing growth of the information industry creates a demand for more powerful databases.
The database products have evolved over time. Initially, databases comprised a simple "flat file" with an associated index. Application programs, as opposed to the database program itself, managed the relationships between these files and a user typically performed queries entirely at the application program level. The introduction of relational database systems shifted many tasks from applications programs to database programs. The currently existing database management systems comprise two main types, those that follow the relational model and those that follow the object oriented model.
The relational model sets out a number of rules and guidelines for organizing data items, such as data normalization. A relational database management system (RDBMS) is a system that adheres to these rules. RDBMS databases require that each data item be uniquely classified as a particular instance of a `relation`. Each set of relations is stored in a distinct `table`. Each row in the table represents a particular data item, and each column represents an attribute that is shared over all data items in that table.
The pure relational model places number of restrictions on data items. For example, each data item cannot have attributes other than those columns described for the table. Further, an item cannot point directly to another item. Instead, `primary keys` (unique identifiers) must be used to reference other items. Typically, these restrictions cause RDBMS databases to include a large number of tables that require a relatively large amount of time to search. Further, the number of tables occupies a large amount of computer memory.
The object oriented database model, derived from the object-oriented programming model, is an alternative to the relational model. Like the relational model, each data item must be classified uniquely as belonging to a single class, which defines its attributes. Key features of the object-oriented model are: 1) each item has a unique system-generated object identification number that can be used for exact retrieval; 2) different types of data items can be stored together; and 3) predefined functions or behavior can be created and stored with a data item.
Apart from the limitations previously described, both the relational and object oriented models share important limitations with regard to data structures and searching. Both models require data to be input according to a defined field structure and thus do not completely support full text data entry. Although some databases allow records to include a text field, such text fields are not easily searched. The structural requirements of current databases require a programmer to predefine a structure and subsequent date entry must conform to that structure. This is inefficient where it is difficult to determine the structure of the data that will be entered into a database.
Conversely, word and image processors that allow unstructured data entry do not provide efficient data retrieval mechanisms and a separate text retrieval or data management tool is required to retrieve data. Thus, the current information management systems do not provide the capability of integrating full text or graphics data entry with the searching mechanisms of a database.
The present invention overcomes the limitations of both the relational database model and object oriented database model by providing a database with increased flexibility, faster search times and smaller memory requirements and that supports text attributes. Further, the database of the present invention does not require a programmer to preconfigure a structure to which a user must adapt data entry. Many algorithms and techniques are required by applications that deal with these kinds of information. The present invention provides for the integration, into a single database engine, of support for these techniques, and shifts the programming from the application to the database, as will be described below. The present invention also provides for the integration, into a single database, of preexisting source files developed under various types of application programs such as other databases, spreadsheets and word processing programs. In addition, the present invention allows users to control all of the data that are relevant to them without sacrificing the security needs of a centralized data repository.